Hydride complexes of ruthenium derived from the heterolytic activation of dihydrogen by amidophosphine complexes

Abstract

The reaction of 〚NPNH〛Ru(η 3:η 2-cyclooctadienyl) ( 1) (where 〚NPNH〛 = {PhNHSiMe 2CH 2P(Ph)CH 2SiMe 2NPh}), an organometallic mono-amide complex of ruthenium(II), with hydrogen gas (1–4 atm) generates three ruthenium hydride species: 〚NPNH〛RuH ( 2), 〚NPNH 2〛RuH 2(C 7H 8) ( 3) and 〚NPNH 2〛RuH 2 ( 4). All of these complexes result from hydrogenation of the cyclooctadienyl group; complexes 3 and 4 also undergo conversion of the amido linkage into a ruthenium hydride and an amine. Complexes 2 and 3 have been characterized both in solution by NMR spectroscopy and in the solid state by X-ray Diffraction and Infrared Spectroscopy. While 4 was fully characterized in solution by NMR spectroscopy, attempts to recrystallize this material yielded 2; the reaction of 2 with H 2 does not produce 4. The starting complex 1 acts as a catalyst precursor for the hydrogenation of imines such as benzylidene aniline; however, none of the isolated hydride species 2, 3 or 4 were active as catalyst precursors.